From UPSC perspective, the following things are important :
Prelims level : Plant growth hormones
Mains level : Not Much
A team of researchers at the Indian Institute of Science Education and Research (IISER), Bhopal, has conducted a study on seed germination that could have a major impact on agriculture.
What is the study about?
- The study aims to determine the optimum timing of seed germination and thus ensure high plant yields.
- It focused on the interplay between plant hormones like abscisic acid (ABA) which inhibit the sprouting of the seed and environmental cues like light (which promotes the sprouting process) and darkness.
Note the following plant hormones and their functions:
|Ethylene||Fruit ripening and abscission|
|Gibberellins||Break the dormancy of seeds and buds; promote growth|
|Cytokinins||Promote cell division; prevent senescence|
|Abscisic Acid||Close the stomata; maintain dormancy|
|Auxins||Involved in tropisms and apical dominance|
What is Abscisic Acid?
- Humans have glands that secrete hormones at different times to stimulate body processes such as growth, development, and the breaking down of sugars.
- Plants also have hormones that stimulate processes that are necessary for them to live.
- Abscisic acid is a plant hormone involved in many developmental plant processes, such as dormancy and environmental stress response.
- Abscisic acid is produced in the roots of the plant as well as the terminal buds at the top of the plant.
Function of Abscisic Acid
Abscisic acid is involved in several plant functions.
- Plants have openings on the bottom side of their leaves, known as stomata. Stomata take in carbon dioxide and regulate water content. Abscisic acid has been found to function in the closing of these stomata during times when the plant does not require as much carbon dioxide or during times of drought when the plant cannot afford to lose much water through transpiration.
- One of the crucial functions of abscisic acid is to inhibit seed germination. Abscisic acid has been found to stop a seed from immediately germinating once it has been placed in the soil. It actually causes the seed to enter a period of dormancy.
- This is of great benefit to the plants because most seeds are formed at the end of the growing season, when conditions would not be favorable for a new plant to sprout. The abscisic acid causes the seed to wait until the time when conditions are more favorable to grow. This ensures greater success in the plant’s ability to grow and reproduce successfully.
- ABA functions in many plant developmental processes, including seed and bud dormancy, the control of organ size and stomatal closure. It is especially important for plants in the response to environmental stresses, including drought, soil salinity, cold tolerance, freezing tolerance, heat stress and heavy metal ion tolerance.